Form relief grinder



W, 9 8- ,P. A. SAAR: ET AL 2,447,138

FORM RELIEF GRINDER Filed Sept. 1, 1944 5 Sheets-Sheet 1 Aug, H7, 1948. P. A. SAARI ET AL FORM RELIEF GRINDER 5 Sheets-Sheet 2 Filed Sept. 1, 1944 Y five/afar; Paul A. Jed

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Aug, 1?, 1948. P. A. SAARI ETAL FORM RELIEF GRINDERv 5 Sheets-Sheet 3 Filed Sept. 1, 1944 Jaye/Zion? Paul A. xy dd'i l flanefli A. Rugg M/ r w w h Aug, 17, 1948. P. A. SAARI ET AL FORM RELIEF GRINDER 5 Sheets-Sheet 4 Filed Sept. 1, 1944 mli fave/lions Pazzi A. Jafii Aug, 17, M4. P. A. SAARl ET AL 2,447,138

FORM RELIEF GRINDER Filed Sept. 1, 1944 5 Sheets-Sheet 5 Patented Aug. 17, 1948 FORM RELIEF GRINDER Paul A. Saari and Herbert A. Rugg, Minneapolis, Minn.

Application September 1, 1944, Serial No. 552,240

12 Claims.

This invention relates to a form relief grinder or to a. machine for grinding a form relief cutter. There are now two main classes of form relief cutters, namely, ground and unground. The so called unground type of relief cutters are formed and finished in lathe; the relief being formed by backing off, and the tool being later hardened. This method produces a relatively rough tool having an objectionable scaly appearance and a gen eral roughness which makes for short life and rough work. The ground type of relief form cutters, on the other hand, have a high finish and long life, but hitherto, the only satisfactory manner of producing these has been by means of very costly special machines built specially for production of each particular tool and capable of being used only for production of that particular tool and even then there have been certain types of tools which could not be produced by automatic grinding machines.

An important object, therefore, of the present invention is the provision of a universal machine which can be used for grinding relief contours of any desired size, shape or character.

It is an object of this invention to provide a method and apparatus for grinding all types of form relief cutters either face type or periphery type, said device also being usable for straight relief grinding. By use of said method and apparatus cutters can be ground either right hand or left hand with equal facility.

It is another object of the invention to provide a grinding device which will produce a uniform relief of true contour from the cutting edge of a tooth to the back of the tooth making possible the maintenance of the accuracy of the cutter through frequent sharpening on the cutting face throughout the entire life of the cutter.

It is a further object of the invention to provide a grinding method and apparatus by means of which all the teeth on a cutter may be accurately and uniformly ground and by means of which a surface will be given accurate relief contour in any two directions at the same time.

It is also an object of the invention to provide a device for grinding a form relief cutter in which the cutter is held on a rotating member and rotated axially and is moved into engagement with the grinding wheel and retracted once for each tooth on the cutter so that all of said teeth are accurately and uniformly ground.

It is still further an object of the invention to,

provide a device for grinding a form relief cutter in which the cutter to be ground can be mounted on a spindle or held in a chuck or be carried on a collet or arbor held between centers.

It is more specifically an object of the invention to provide a device for grinding a form relief cutter comprising a rotatable member on which the cutter is carried and axially rotated, a cam rotated in synchronism with said cutter, preferably through change gears, a reciprocating member movable to various angles about a vertical axis and carrying said first mentioned member and reciprocated by said cam to move a cutter against a grinding wheel, said member being reciprocated once for each tooth on said cutter so that the ground surface of each tooth is accurately and uniformly ground and a uniform relief is produced on the tooth surface from the cutting edge back to the end of the tooth.

Another object of the invention is to provide a machine and method for accurately grinding a cutter by means of which a proper contour is given to the grinding wheel surface for eliminating error and securing accuracy on the tooth surface of said cutter.

These and other objects and advantages of the invention will be fully set forth in the following description made in connection with the accompanying drawings in which like reference characters refer to similar parts throughout the several views and in which- Fig. l is a semi-diagrammatic view partly in side elevation and partly in perspective, some parts being indicated in dotted lines;

Fig. 2 is a view partly in sid elevation and partly in central vertical section taken through the axis of the rotating member which carries the cutter;

Fig. 3 is a view partly in plan and partly in horizontal section taken substantially on line 33 of Fig. 2 as indicated by the arrows, some parts being broken away and others shown in further horizontal section;

Fig. 4 is a view partly in end elevation and partly in vertical section taken substantially on line 4-4 of Fig. 2 as indicated by the arrows;

Fig. 5 is a View partly in plan and partly in horizontal section taken on line 55 of Fig. 2 as indicated by the arrows;

Fig. 6 is a view similar to Fig. 5 showing the parts in different position; v

Fig. '7 is a view in side elevation somewhat diagrammatically illustrating the position of the cutter and grinding wheel;

Fig. 8 is an end view of the cutter shown in Fig. 7 as seen from the right hand side thereof;

Fig. 9 is a view similar to Fig. 7, showing the grinding wheel in postion for grinding a different surface of the cutter;

Fig. is a view in side elevation illustrating the position of the grinding wheel and a cutter for grinding certain tooth surfaces, a different position of the wheel being shown in dotted lines;

Fig. 11 is an end view of the cutter shown in Fig. 10 as seen from the right of Fig. 10;

Fig. 12 is a view similar to Fig. 10 but showing the grinding wheel in a position for grin-ding different tooth surfaces on the cutter; and

Fig, 13 is a view in side elevation illustrating a device for dressing a grinding Wheel.

Referrin to the drawings, a machine is shown comprising a head portion bored to provide a bearing for rotating tool-carrying member 2!. Head 20 i provided with a fiat surface on its top forming the supporting surface for an electric motor 22 having a pulley 23 secured to the driving or armature shaft thereof. A belt 24 runs over pulley 23 and over a second pulley 25 mounted upon a shaft 26 journaled in a suitable bearing portion 21 and having secured to its end opposite pulley 25, a worm gear 29. Worm gear 29 meshes with the worm wheel gear 30 secured to one end of a shaft 3! journaled in a suitable bearing portion 32 and having secured thereto a spiral or helical gear 33. Gear 33 meshes with another spiral or helical gear 34 which is in turn secured to a shaft 35 journaled in suitable bearings in the lower part of the head portion 20. A gear 31 is secured adjacent one end of shaft 35, the same being illustrated as held in place by a nut 38. Gear 31 meshes with a gear mounted on a stud 4| carried in one end of an arm 42, which has a hub portion carried on and oscillatable on shaft 35. Gear 40 meshes with another gear 43 which is carried adjacent one end of rotating member or spindle 2| and which will be held in place by a nut 44. The gears 31, :20 and 43 together with the swinging arm 42 and stud 4|, constitute a change gear arrangement so that different gears may be used to obtain different speed ratios between the rotation of spindle 2| and shaft 3!. Shaft 3| has secured adjacent its lower end a cam 46. Cam 45 is shown as secured by a nut 4'1, The showing in Fig. 1 as stated, is somewhat diagrammatic and the parts are shown as separated or spaced more than they actually are in the machine, which is more properly shown in Fig. 2. In Fig. 2 nut 4'! is shown as of cylindrical form. The head portion 20 is integrally connected to a rotatable member 48.

The cutter to be ground which is illustrated as 59 in Fig. 1, has a cylindrical or spindle portion a which may be conveniently held in a suitable rotary work holder such as a chuck 5! carried at the front end of member 2 I A member 52 is provided which is secured at one end of the head 20 and has a cylindrical portion 52a projecting therefrom. A head 53 is mounted on portion 52a for a non-rotating sliding movement thereon and said member can be locked in different positions on portion 52a by a locking mechanism operated by a lever 53a. Member 53 is bored to receive a spindle 54 which may carry a center 55. A center could also be carried in the chuck 5| so that if desired the cutter to be ground could be mounted on a collet or arbor held between the center 55 and the center of chuck 5!; said centers then serving together as a rotary work holder. Such a construction for holding the cutter is shown in Figs. 10 and 12. A wedge key shaped member 49 is slidable in .a groove 52b in the bottom of member 52. A gib 56 underlies member 49 and can be moved lengthwise to a screw 51 threaded in member 26 and engaging gib 56. Member 49 can be moved longitudinally to wedge between members and 52 by turning a pin 58 journalled in head 2%) and having an eccentric portion 58a disposed in a slot 490 of member 49. Pin 58 will be turned by a handle 58 at one side of head 20. Member 52 can thus be locked in position by so moving member 43.

The head portion 23 and parts carried thereby can be rotated with member 48. A grinding Wheel 56 is shown as carried on a shaft 6| to which is secured a pulley 62 driven by a belt 53. The grinding wheel 60 can be mounted in any desired manner either on the frame of the grinding machine or on a separate frame. Said grinding wheel is usually mounted so that it can be moved vertically and held in different vertical positions. Member 48 is mounted for oscillation on a member 55. Member 58 is shown as having spaced parallel elongated lugs 38a at one side thereof and on its top over which a bracket 66 is adapted to fit, said bracket being secured by a screw 61 having its head countersunk in said bracket. Bracket 66 forms a support for member 52 to which latter it is secured by the spaced headed screws 68. Cam 4-6 is engaged by a cam roller 10 carried on a stud ii mounted in the arms of a fork formed at one end of a lever arm 12 which is secured at its other end to a shaft 13. While lever 12 could be attached in any desired manner, in the embodiment of the invention illustrated it is shown as having a split hub with projecting arms through which extends a clamping screw 14. A pin 12a is secured to lever 12, the same having a hooked upper end over which is disposed one end of a tensile coil spring 68, the other end of which is secured to a pin 68a secured in any suitable positie-n in member 29. Shaft 73 is journaled in a bushing or sleeve 15 mounted in a bore in member 48. Said bushing 15 is threaded at its upper end to receive a nut 16 shown as having slots or flutes in its edge adapted to receive a suitable spanner wrench or tool for turning the same. Member i5 also extends into a bore in member 65 and has a flange at its lower end seated in a counterbore in member 65. Members 48 and 55 are thus held in position vertically by member #5. By loosening nut 16 members 48 and 55 can be relatively rotated. Shaft 13 has a lower end of greater transverse dimension than the bore in member '15 forming a shoulder extending beneath member 15, and said end is elongated to form an arm Ha. Said portion of said member or arm Ha is provided with a slot 1|=b extending longitudinally thereof and :open at its lower side. A bar Bil of rectangular form in transverse cross section is fitted in a groove in a guide member 8| underlying member 55. A block 82 of square or rectangular form is disposed in slot ill) and is secured to bar 88 by a threaded stud 83. Member 55 is provided with a dove-tailed groove or slot 65a at its underside in which fits the dove-tailed upper part 81a of member 8|. Said part 8la is discontinued at the intermediate part of member 8! and the adjacent inner ends 8|b thereof extend at an angle as shown in Figs. 1, 5 and 6. Member 8| has a substantially cylindrical flange 8E0 at its lower side from which extends downwardly a cylindrical portion 81d. Portion Bld is received in the bore of a slide or base member 85 adapted to rest and slide longitudinally on a frame portion of the machine not shown. Member 85 is provided with an inverted V-shaped groove 85a at its underside and adjacent one longitudinal edge thereof, adapted to fit over a V-shaped rib on said frame. Member 85 is shown in Fig. 3 and has open ended slots 85b at each end thereof surrounded by raised finished bosses 85c. Bolts 86 are adapted to extend through the slots 85b, which bolts will have T-shaped heads disposed in a T-slot in the frame on which member 85 slides. Washers ill are preferably disposed on the bosses 85c underlying the nuts 88 on the upper ends of bolts 88. Member 85 can be locked to said frame by tightening bolts 86. Portion 8ld is provided with a groove Sle of angular shape in vertical cross section, which groove extends circumferentially around portion Bid. A ring 90 has an inner side of angular shape extending into the groove Me, which ring is split and has spaced radially projecting ends 95a as shown in Fig. 3. Ring 90 is adapted to be tightened by a headed screw 9! extending through one end of said ring and tapped into the other end thereof. Ring 9i] is provided with a recess 90b at one side forming a shoulder through which screw 9| extends. Ring 90 is disposed in a cylindrical recess 35d formed in the lower side of member 85. When screw 9| is tightened ring 98 is contracted and cams upward in annular groove 8le thus engaging member 85 with its upper surface and frictionally locking member 8| in position.

Member 65 has an upstanding boss 55b adjacent one end which is bored to receive a member 93 which extends downwardly into a slot 8| in one end of member 81. Member 93 is bored and threaded to receive one end of a screw 94 extending through the bore in the end of member 8! and extending longitudinally thereof. Screw SM is provided with a bore at its inner end in which is disposed one end portion of a compression coiled spring 95, the other end of which is seated in a bore 3 ig in member 8 l. Screw 9! is provided with a slot at one end adapted to receive a suitable tool for turning and adjusting the same.

Member 65 is provided with a bore 650 between boss 65b and bushing '55, the same having its center in a line extending from the bore in boss 65b and the axis of member E5. A plug 91 is disposed and fixed in bore 650 and has a downwardly flaring frusto-conical recess 91a in its lower side. Member 8! is provided with a bore Blh in which is secured a shell 9% Another shell 99 is fitted into shell 58 and has a bore therein open at its upper end and formed at its bottom with a horizontal flat surface. A plunger member l8! having a frusto-conical upper end constructed and arranged to fit in recess 910, has its lower portion fitted in and secured to shell 99. Plunger I [H has a bore opening at its lower end. A small plunger I93 rests on top of pin I99 Within shell 99 and is movable in the bore in member ml. A small compression coil spring I04 has its lower end seated in a bore in plunger H33 and its upper end seated in a small counter bore in plunger I0! A pin It!!! extends transversely through member 8! and through the bore in. shell 99. Pin 100 is provided with a slot 580a at one end adapted to receive a suitable tool for turning the same. Within shell 99 pin we is cut away at one side of its diameter so as to be semi-cylindrical in cross section. With pin A89 in the position shown in Fig. 2, plunger Hi! seats in recess 81a and looks members 65 and 85 together with the mark Mi aligned with the central graduation 65c. If parts 55 and BI were moved with considerable force plunger It! would cam out of recess Ma, and prevent damage. When pin Hill is turned 180 degrees it moves shell 99 and plunger llH downwardly against the pressure of spring I04 and releases or disconnects members 65 and 8| so that member 65 can be reciprocated. When changing the direction of slide 65a it is necessary to loosen cam lever screw 14, and unless slide 65a is locked spring 95 will push member 65 to its extreme backward position. The lock pin therefore makes it possible to change the direction of the reciprocating slide without losing the loading of spring 95.

In operation if it is desired to grind the surface 50a of cutter 50 the grinding wheel will be disposed relatively to the cutter as shown in Fig. 9. This is also the position of wheel 60 shown in Fig. i. This relation of the cutter to the grinding wheel is customarily made by swinging member 8| about the axis of its projection Bid. For this operation wheel 60 is so disposed that the cutter 58 can be moved against grinding face 60a by an axial movement of cutter 59. When motor 22 is operated pulley 25 will be rotated and this will, through the gears 29, 30, 33 and 3G, rotate shaft 3! and cam 45. The spindle 2i and chuck 5| will also be simultaneously rotated through gears 31, MI and 43. Cam 46 is thus rotated in synchronism with cutter 5G. Roller 10 is held against cam 46 by spring 68. At each rotation of cam 46, roller H! will be moved away from shaft ll at the high part of the cam, thus swinging lever 72 and rotating shaft 73. This oscillates the arm 1 la and this arm engages block 82 secured to bar 80 and tends to oscillate said bar. Since member 8| in which bar 89 is disposed is stationary, said bar cannot be oscillated but the reaction through the arm 8! causes a reciprocation of member or slide 65. Since slide carries the head 20 and spindle 2|, the tool 59 will be reciprocated with the slide 65. When tool 50 is thus reciprocated, it is moved against the grinding wheel 60 and its grinding surface 68 and is then retracted. The change gears 31, M3 and 43 will be so selected that there will be one complete reciprocation of cutter 50 for each tooth of the cutter. The reciprocation is timed so that the cutter tooth is against the grinding wheel long enough to grind the circumferential extent of the tooth surface. It is moved toward the grinding wheel throughout said extent and is then retracted. As both the cutter and the grinding wheel are rotating about fixed axes, the cutter will thus be very accurately and uniformly ground. The surface 5% on each of the teeth is thus properly ground and finished and given the desired contour for clearance. The cutter will first engage the grinding surface of wheel 50 adjacent the face of the tooth. It will continue to move toward said grinding surface as the cutter is rotated and the clearance or relief will thus be produced. This relief is given by a slight gradual reduction of the radius of the ground surface or by a slight gradual recession rear- Wardly on an end surface. The slide G5 is moved in one direction by arm H a and is moved in the other direction by spring 85. It will be seen that spring 95 is compressed when the cutter is moved toward the wheel. Screw 84 can be adjusted to vary the tension on spring 95. Bar can be adjusted lengthwise in its groove in member 8!. This changes the distance between the centers of shaft 13 and block 81 and thus varies the amplitude of reciprocation of slide 65 and thus of the cutter being ground. The member 8| on one side is provided with a gauge mark 8h adapted to cooperate with a plurality of gauge marks 65c on the side of slide 65. The amplitude of reciprocation of slide 65 can thus be noted. Members 85 and 8! can be rotated to give the desired position to the cutter being ground. When they are at a 45 degree angle and an end surface such as said surface 50a (Fig. 9) is being ground the relief circumferentially on said surface will be equal to the endwise relief. If the angle is less or more than 45 degrees the relief in one direction will be greater and that in the other direc tion correspondingly less. If the surface 50b on the tool Ell is to be finished, the grinding wheel Bil will be disposed relatively to the cutter as shown in Fig. '7. A tool 500 such as shown in Fig. 10, can be ground on the various surfaces of its teeth by disposing the wheel as shown in Figs, 10 and 12. With the wheel positioned in full lines in Fig. 10, the surfaces 500a will be finished and with the wheel disposed in dotted lines in Fig. 10, surfaces 59% will be finished. With the tool disposed as shown in Fig. 12, the surfaces fillflc on the teeth will be finished. It will be noted that the cutter is moved in a direction longitudinally of slide 65. This can be disposed at various angles to the axis of the cutter. The angle between the axis of member 2! and the cutter is varied by rotating head 20 about the axis of shaft 15. This can be done by loosening nut if. It will, of course, be appreciated that for grinding some other contours the reciprocation of the tool will be in directions other than axial of the tool. From the above it will be clear that either spiral relief or helical relief or a combination of both can be attained.

Since both the wheel and the cutter are rotating as shown in Fig. 7, the inner part of surface 501) in the rotation of the cutter will reach the grinding surface before the outer portion of said surface or the portion on the greater radius because of the peripheral curvature of the grinding wheel. For this reason, in order to properly finish surface or to get a surface having straight line elements, the grinding wheel should have its grinding face on a curve as shown in Fig.7. The machine can be used to properly dress wheel 60 to give the desired surface curvature by having a holder E20 disposed in chuck 5i, which holder is slotted to receive a bar or dressing tool i2i. Tool l2! has a pointed projecting operating :portion 52! a which in practice is usually a diamond. By rotating spindle 2i and chuck 5! and simultaneously rotating grinding wheel 69, the grinding surface can be properly dressed and shaped by moving the tool l25 longitudinally or disposing it in successively different positions in its holder I20. This operation is part of applicants novel method. From the above it will be clear that the same identical kind and combination of movements as tend to produce an objectional or erroneous curvature on the tool can be utilized to generate a compensating curvature on the grinding wheel surface. In grinding a straight cutting edge on the end of a tool which is rotating and moving forward at the same time, an objectionable curvature inwardly toward the center is produced because the grinding wheel is round. To correct this, we generate an opposite curvature on the periphery of the grinding wheel by passing a hard dressing edge (preferably a diamond) back and forth across the periphery of the wheel and occupying the exact position that the cutter will later occupy, because the grinding wheel cannot grind the diamond the diamond generates exactly the opposite curvature on the periphery of the Wheel that a transversely fiat wheel would produce on the surface of the work and the overall result is a straight line grind when the surface corrected grinding wheel is employed.

From the above description it will be seen that we have provided a novel and comparatively simple and very efficient method and machine for accurately and uniformly grinding form relief cutters. It will be understood that such cutters are commonly used for cutting and milling operations, the same having the cutting surfaces either on the periphery or on their ends. By the use of the method and machine, each tooth is ground exactly as is every other tooth on the cutter and a proper contour is given to the tooth and a uniform relief provided on each tooth. The accuracy of the cutter will thus be maintained through frequent sharpenings and throughout the entire life of the cutter. Greater tooth strength can be secured and breaking down of the cutting edges prevented. By use of the generating process described in the preceeding paragraph, the radial error on end tools can be completely corrected. The method and machine have been amply demonstrated in actual practice and found to be very successful and efficient. Tools of many kinds have been perfectly ground, some of which it was previously impossible to grind.

It will of course, be understood that various changes may be made in the steps and sequence of steps of the method and in the form, details, arrangement and proportions of the parts without departing from the scope of applicants invention, which generally stated, consists in a method and apparatus capable of carrying out the objects above set forth, and such as described and defined in the appended claims.

What is claimed is:

1. A device for grinding a form relief cutter on a grinding wheel having in combination, a rotatable member carrying said cutter and rotatable therewith, means for rotating said member, a rotatable cam, gearing connecting said means and cam whereby said cam is rotated in synchronism with said rotatable member, a slide carrying said member, an oscillating member actuated by said cam, a member moved by said oscillating member and engaging said slide to reciprocate the latter longitudinally once for each tooth on said cutter whereby said cutter is moved against said wheel to grind each tooth thereon and is moved away from said wheel between said teeth.

2. The structure set forth in claim 1 and means for positioning the longitudinal axis of said slide at various angles to the axis of said rotatable member.

3. The structure set forth in claim 2 and means for positioning said rotatable member and second member with the axis of the former at various angles to the line of reciprocation of the latter.

4. A device for grinding a form relief cutter on a grinding wheel having in combination, a rotatable member carrying said cutter co-axially therewith, means for rotating said member and cutter, a rotatable cam, means for rotating said cam from said means whereby said cutter and cam rotate in synchronism, a second member movable rectilinearly and carrying said rotatable member, an arm oscillating about a fixed axis, means connecting said arm and second member, means connecting said cam and arm to oscillate the latter whereby said second member and said cutter are reciprocated toward and from said wheel once for each tooth on said cutter.

5. The structure set forth in claim 4 and means 9 for varying the amplitude of reciprocation of said member and cutter.

6. The structure set forth in claim 4 and means for varying the distance between said third mentioned means and said axis to vary the amplitude of reciprocation of said second member.

7. A machine for use with a grinding wheel for form relief grinding on tools and the like comprising a base member, a guide member mounted on the base member for adjustments about an axis, a slide member carried by the guide member, said guide member and slide member having cooperating guide portions guiding the slide member for straight line reciprocating movements on the guide member on a plane perpendicular to the axis of adjustment between the guide member and base member, a head member carried by the guide member, means anchoring the head member to the slide member for adjusting movements about an axis parallel to the axisof adjustment between the base member and guide member and perpendicular to the plane of reciprocation of the slide member on the guide member, a work-carrying spindle journalled to the head member on an axis perpendicular to the axes of adjustment between the base member and guide member and %tween the head member and slide member, means imparting unidirectional rotation to the spindle, and power transmission connections between the spindle and slide member imparting limited reciprocating movements to the slide member on the guide member in predetermined timed relation to spindle rotation; said power transmission connections comprising a shaft coaxial with the axis of adjustment of the head member and extending through the slide member.

8. A machine for use with a grinding wheel for form relief grinding on tools and the like comprising a base member, a guide member mounted on the base member for adjustments about an axis, a slide member carried by the guide member, said guide member and slide member h'aving cooperating guide portions guiding the slide member for straight line reciprocating movements on the guide member on a plane perpendicular to the axis of adjustment between the guide member and base member, a head member carried by the guide member, means anchoring the head member to the slide member for adjusting movements about an axis parallel to the axis of adjustment between the base member and guide member and perpendicular to the plane of reciprocation of the slide member on the guide member, a work-carrying spindle journalled to the head member on an axis perpendicular to the axes of adjustment between the base member and guide member and between the head member and slide member, means imparting unidirectional rotation to the spindle, and power transmission connections between the spindle and slide member imparting limited reciprocating movements to the slide member on the guide member in predetermined timed relation to spindle rotation; said power transmission connections comprising a shaft coaxial with the axis of adjustment of the head member and extending through the slide member, a lever carried by the end portion of said shaft adjacent the guide member, and a sliding connection between the guide member and said lever converting rotary motion of the lever into straight line reciprocating movements of the slide member and parts carried thereby.

9. A machine for use with a grinding wheel for form relief grinding on tools and the like comprising a base member, a guide member mounted on the base member for adjustments about an axis, a slide member carried by the guide member, said guide member and slide member having cooperatin guide portions guiding the slide member for straight line reciprocating movements on the guide member on a plane perpendicular to the axis of adjustment between the guide member and base member, a head member carried by the guide member, means anchoring the head member to the slide member for adjusting movements about an axis parallel to the axis of adjustment between th'e base member and guide member and perpendicular to the plane of reciprocation of the slide member on the guide member, a work-carrying spindle journalled to the head member on an axis perpendicular to the axes of adjustment between the base member and guide member and between the head member and slide member, means imparting unidirectional rotation to the spindle, and power transmission connections between the spindle and slide member imparting limited reciprocating movements to the slide member on the guide member in predetermined timed relation to spindle rotation; said power transmission connections comprising a shaft coaxial with the axis of ad" justment of the head member and extending through the slide member, a lever mounted on said shaft adjacent the guide member and having a guideway extending substantially radially thereof, and a pin carried by the guide member and working in the guideway of said lever.

10. The structure defined in claim 9 in which the said pin is adjustably mounted on the guide member on a line transversely of the direction of reciprocation of the slide member, whereby to vary the extent of reciprocation of the slide member responsive to angular movements of said shaft.

11. The structure defined in claim 10 in which the said pin is mounted on a bar that is slidably adjustably mounted in the guide member.

12. The structure defined in claim 11 in which the said pin is mounted on a bar that is slidably adjustably mounted in the guide member for adjusting movements substantially radially of the said shaft.

PAUL A. SAARI. HERBERT A. RUGG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 821,849 Benicke May 22, 1906 1,285,124 Gleason Nov. 19, 1918 1,377,884 Heryngfel May 10, 1921 1,616,056 Mensforth et a1. Feb. 1, 1927 2,099,724 Cogsdill Nov. 23, 1937 2,217,091 Zwick Oct. 8, 1940 

